myClass := MyDemo.
myClassName := MyDemo name.
snapshot := (MCPackage new name: myClass package name) snapshot.
memory := FileSystem memory. 
writer := TonelWriter on: memory root.
writer writeSnapshot: snapshot.
"Remove package"
myClass package removeFromSystem.
"Find myClass file"
classDefinition := snapshot definitions 
    detect: [ :e | e isClassDefinition and: [ 
            e className = myClassName ] ].
dir := writer packageDir.
fileName := writer fileNameFor: classDefinition.
(dir / fileName) contents.
"Read and Install definitions"
reader := writer class readerClass on: memory root.
reader packageDirectory: dir basename.
reader loadDefinitions.
reader snapshot install.